In the above-identified Applications, there are described several different techniques for forming a protective covering on the exterior surface of a photoflash lamp for eventual use in a photoflash device. Such devices, and particularly those defined above, include several (e.g., 4, 6, 8 or 10) such lamps as part thereof, along with various additional components such as circuitry (for those which are electrically activated), reflectors, switches, etc. Examples are shown and described in U.S. Pat. Nos. 4,268,891 (B. G. Brower et al), 4,249,230 (W. T. Colville et al), 4,200,901 (J. W. Shaffer et al), and 4,186,424 (T. Fohl.). All of these patents are assigned to the assignee of the instant invention.
With particular regard to multilamp photoflash devices which are electrically activated (e.g., by the power source typically found in many of today's cameras when the device is inserted in a socket typically found on such cameras), such devices typically require a sequencing circuit to assure sequential ignition of each lamp therein in response to receipt of a high voltage pulse provided by the aforementioned camera power source (e.g., a piezoelectric element). To assure this sequential ignition, the circuitry includes various switching components, a preferred example being the radiant energy-activated disconnect switch defined in U.S. Pat. No. 4,017,728 (E. G. Audesse et al), said patent also assigned to the assignee of this invention. As defined therein, this member is readily capable of being severed (disconnecting) to provide an open circuit thereacross upon receipt of radiant energy in the form of light and/or heat from a nearby photoflash lamp when said lamp is fired (ignited). The subsequent manner of operation of the circuit is described fully in U.S. Pat. No. 4,017,728 and is now well established in the art, further definition thereof not believed necessary.
There are described in copending Applications under Ser. No. 183,915 now U.S. Pat. No. 4,375,953, and Ser. No. 262,008 now U.S. Pat. No. 4,424,020, subminiature photoflash devices which employ several (e.g., 10) subminiature photoflash lamps. As defined therein, the completed devices preferably include switching means so as to assure sequential lamp ignition. The chosen means suggested in Ser. No. 183,915 is to orient the lamp-firing circuitry and switch components (preferably those of the variety described in U.S. Pat. No. 4,017,728 above) on an external surface of the device's substrate member and provide contact thereto between the lamps and switches by forcing the lamp lead-in wires through the substrate, said wires penetrating the circuit paths at preestablished locations. Understandably, the mode of connection necessitates placement of the disconnect switch on the same side of the substrate as the circuitry, thus locating these components at an undesirable spaced (the substrate thickness) location from the activating lamps. This position relationship was believed necessary in Ser. No. 183,915 when using the described cover means and particularly when using an encapsulating-type material to encase the lamp. In the device described in Ser. No. 262,008, it is taught to place the switch on the same side of the substrate as the activating photoflash lamps. However, the means for providing a cover for said lamps involves use of a hollow-type, plastic light-transmitting member of a type similar to those used in many of the aforementioned, earlier devices. Use of such a cover adds appreciably to the overall volume of the finished product and, in most instances, still necessitates provision of a separate protective covering (e.g., coating) for each lamp located therein. With particular regard to photoflash devices of the subminiature variety, such as those shown in Ser. No. 183,915 and Ser. No. 262,008, a preferred means for providing a protective covering on each lamp is to cover the lamp with a resin material capable of eventually forming a solid, light-transmitting polymer upon curing thereof. As stated, examples of providing such a covering are described in the aforementioned copending applications, particularly those under Ser. Nos. 308,698 and 308,637. Use of this type of covering assures a solid, robust finished article of smaller dimension than those requiring the aforementioned, hollow cover, while at the same time enabling proper light emission and providing positive lamp containment during ignition thereof.
In accordance with the teachings of the instant invention, there is described a photoflash device wherein the relatively delicate radiant energy-activated disconnect switch is positioned immediately adjacent the respective photoflash lamp and thus on the same side of the device's substrate, and a solid, light-transmitting polymer material (such as defined in Ser. No. 308,698 and Ser. No. 308,637) positioned about the lamp and providing a protective coating therefor. The lamp is thus able to activate the switch in a facile manner, the switch is assured of being positively connected to corresponding circuitry, and the highly advantageous polymer covering can still be utilized. Surprisingly, the liquid resin which eventually forms the solid polymer can be used without adversely affecting the operational capability of the switch member.
It is believed, therefore, that a photoflash device possessing the several features described above would constitute an advancement in the art.